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Saturday, 23 March 2013

NASA on asteroid defense: If it’s coming in three weeks, pray

Many captured video or photographs of the asteroid that exploded over Russia February 15, 2013.

The U.S. House Science, Space, and Technology Committee met in a hearing on March 19, 2013 to discuss threats from space.

On February 15, a small asteroid exploded over Chelyabinsk, Russia,
generating shock waves that shattered windows and injured some 1,500
people. On that same day, asteroid 2012 DA14 made a close pass by Earth,
at a scant 17,200 miles (27,700 km) from our world’s surface, closer
than some communication satellites. In response to these events, the
U.S. House Science, Space, and Technology Committee met in a hearing on
March 19, 2013. The hearing was titled Threats from Space: A Review of U.S. Government Efforts to Track and Mitigate Asteroids and Meteors. Scientists
and lawmakers discussed the risk of, and defense strategy for, an
unforeseen asteroid or meteor on collision course with Earth. While
trying to emphasize the need for adequate funding for detecting and
characterizing near-Earth objects, and diverting them if necessary, NASA
Administrator Charles Bolden said:

From the information we have, we don’t know of an
asteroid that will threaten the population of the United States. But if
it’s coming in three weeks…pray.

In other words, unless we know in advance that an asteroid is coming –
and therefore have time to divert it – there is little we could do
about an asteroid on a collision course with Earth. Bolden added:

The reason I can’t do anything in the next three weeks is because for decades we have put it off.

All
asteroids within a third of Earth’s distance from the sun in
mid-February, 2013 are shown, with Earth at the center, in pseudo 3D.
The red oval around Earth represents a distance 10 times greater than
the moon’s distance. View larger..

Computer-generated image via Scott Manley at Armagh Observatory

NASA is currently tracking about 95 percent of Near Earth Objects
(NEOs) that are .62 miles (nearly 1,000 meters) or larger in diameter.
White House Science Advisor John Holdren told legislators that:

… an asteroid of that size, a kilometer or bigger, could plausibly end civilization.

So far, none of the objects NASA is tracking appear to be an immediate threat. However, as Chairman Smith pointed out:

The meteor that struck Russia was estimated to be 17
meters and wasn’t tracked at all. The smaller they are, the harder they
are to spot, and yet they can be life-threatening. Some space
challenges require innovation, commitment and diligence. This is one of
them.

A small asteroid – like the one that exploded over Russia on February
15 – would not be world destroying. But clearly objects smaller than
.62 miles (1,000 meters) have the potential to cause damage.
Representative Eddie Bernice Johnson (D-TX) said the events on February 15:

… serve as evidence that we live in an active solar
system with potentially hazardous objects passing through our
neighborhood with surprising frequency.

Artist’s concept of asteroid 2012-DA14, via NASA

John Holdren said the best way to detect objects that might be on a
collision course with Earth would be to put an infrared-sensing
telescope in a Venus-like orbit. Holdren estimated the cost of such a
telescope to be between $500 million and $750 million. Another costly
and time-intensive undertaking would be mounting a mission to divert a
threatening object after detection. NASA’s hunt for threatening
asteroids will be affected by federal sequestration cuts, and at present
funding levels NASA estimates it will take nearly 20 years to identify
all potentially threatening Near Earth Objects.

One solution that all lawmakers seemed amenable to was crowdsourcing, that is, working with other countries and amateur astronomers to crowdsource the hunt for threatening asteroids. Holdren said:

The odds of a Near-Earth Object strike causing massive
casualties and destruction of infrastructure are very small, but the
potential consequences of such an event are so large it makes sense to
take the risk seriously.

Bottom line: On March 19, 2013, the House Science, Space, and Technology Committee met in a hearing titled Threats from Space: A Review of U.S. Government Efforts to Track and Mitigate Asteroids and Meteors.
Legislators, NASA administrators and others discussed the need for
adequate funding for detecting and characterizing near-Earth objects,
and diverting them if necessary.

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